<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>常用样式</title>
		<style>
			.mydiv{
				width: 300px;
				height: 300px;
				background-color: aqua;
				color: white;
				margin: 0 auto;
				text-align: center;
			}
			.uname{
				width: 420px;
				height: 40px;
				border-radius: 8px;
				/* border: 1px solid red; */
				border: 1px dotted #6cf;
				background-color: azure;
			}
		</style>
	</head>
	<body>
		<h1>背景样式</h1>
		<div class="mydiv">
			今天天气真不错了
		</div>
		<h1>边框样式</h1>
		用户名<input type="text" class="uname">
	</body>
</html>